His career was closely associated with - and somewhat overshadowed by - William Lyon Mackenzie, the Reform agitator, mayor of Toronto, and Rebellion leader.
However, as a leader himself, Lesslie took a prominent role in founding the Mechanics Institute (for adult education), the House of Refuge & Industry (a shelter for the unemployed), the Bank of the People, as well as the political parties known as the Canadian Alliance Society and Clear Grits.
In many respects, Lesslie's life ran in parallel to Mackenzie's, from their birth in Dundee, their immigration to Upper Canada, their albeit brief business partnership, to their lifelong commitment to Reform politics.
[3] "Muddy York" was municipally governed by the Court of Quarter Sessions, composed of appointed magistrates; these men were part of the Family Compact.
In 1833, several prominent reformers petitioned the House to have the town incorporated (Upper Canada's first), which would also have made the position of magistrate elective.
The Tory-controlled House struggled to find a means of creating a legitimate electoral system which might, nonetheless, minimize the chances of Reformers being elected.
The bill passed on March 6, 1834, and proposed two different property qualifications for voting; a higher one for the election of aldermen (who would also serve as magistrates), and a lower one for common councillors.
The Canadian Alliance Society shared the same space in the Second Market Building as the Mechanics Institute and the Children of Peace, an active reform religious group from the village of Sharon, Ontario.
The first petition campaign of the Canadian Alliance Society originated with the Children of Peace, and asked for a "Provincial Loan Office.
[5] In 1834, the United Kingdom passed a new Poor Law which created the system of Victorian workhouses (or "Houses of Industry") that Charles Dickens described in Oliver Twist.
The Toronto House of Industry was started by the reformers in the ‘unused’ courthouse on Richmond Street in January 1837 where they had previously met as the "Canadian Alliance Society" of which Lesslie had been president.
A constant struggle between the ruling elite, the "Family Compact," and the Reformers to gain control of the institution prevented this plan from ever fully being implemented.
He and other disappointed Reformers then formed the Mississippi Emigration Society which proposed to purchase a large block of land at Davenport, Iowa for the erection of a mill, other property to be held in common, and redistribution among shareholders.